During your progress in the story mode of Resident Evil 2, you will eventually reach a research lab with a greenhouse. It can be considered a tricky part of the game due to the difficult puzzles.
Resident Evil 2 has a lot of difficult encounters like getting chased by Resident Evil 2 Tyrant Mr. X. We have already covered the safe, codes, and lock solutions in Resident Evil 2, explained the difficulty modes and talked about the different variations for the Samurai Edge handgun so now here is something focused on the Resident Evil 2 Greenhouse and its Lab codes.
To begin first, you will have enter two codes here. The first code will unlock a ladder leading down to the basement. The second code will unlock the synthesizer which is required for one of the puzzles.
The codes are input on a numeric keypad but with symbols instead of numbers. Assuming the keypad starts from 1 to 9 and the bottom middle button is 0, here is what you need to input on the keypad in order to solve the lab codes and finish this puzzle.
To do this puzzle, you will have to grab Dispersal Cartridge from the Control Room in the Greenhouse. Once you have found it, you have to use the lab codes to unlock the synthesizer.
You have to press three colored buttons that are visible at the button of the synthesizer. Starting from the default position, you have to press them in the following order.
That should get you the required result and solve the puzzle. Once you have the Herbicide, it will have to be cooled down and you can do this by heading into the basement.